A. Field of the Invention
The present invention relates to lighting fixtures that produce high intensity, controlled, and concentrated light beams for use at relatively distant targets. In particular, the invention relates to such lighting fixtures, their methods of use, and their use in systems where a plurality of such fixtures are used in combination, usually elevated on poles, to compositely illuminate a target area energy-efficiently, with reduced glare and spill light, and with the capability to lower capital and/or operating costs. One primary example is illumination of a sports field.
B. Problems in the Art
This general configuration of sports lighting fixtures 2 (see FIGS. 1A-G) has remained relatively constant over many years because it is a relatively economical and durable design. It represents a reasonable compromise between the desire to economically control high intensity light to a distant target while at the same time minimizing wind load, which is a particularly significant issue when fixtures are elevated out-of-doors to sometimes well over 100 feet in the air. A much larger reflector could control light better. However, the wind load would be impractical. A significant amount of the cost of sports lighting systems involves how the lights are elevated. The more wind load, the more robust and thus more expensive, the poles must be.
In recent times, sports lighting has also had to deal with the issue of glare and spill light. Therefore, competing interests and issues provide challenges to sports lighting designers. Some of the interests and issues can be at odds with one another. For example, the need always remains for more economical sports lighting. On the other hand, glare and spill control can actually add cost and/or reduce the amount of light available to light the field. Designers have to balance a number of factors, for example, cost, durability, size, weight, wind load, longevity, and maintenance issues, to name a few. Attempts to advance the art have mainly focused on discrete aspects of sports lighting. For example, computerized design of lighting systems tends to minimize hardware costs and system installation costs but uses conventional lamp and fixture technology, with their weaknesses. Also, larger lumen output lamps produce more light, but are used with conventional fixture technology. A need, therefore, still exists for advancement in the art of sports lighting.
Current wide or large area lighting systems suffer from such things as energy lost in conversion of electricity to light energy; energy lost in the lighting fixture; and energy lost in light going to unintended or non-useful locations. The present invention addresses these issues.